Currently, supercritical pseudo-boiling two-phase heat transfer is at the forefront of research. However, existing theories mainly focus on pseudo-interface evaporation, whereas the exploration of bubble-like interfacial dynamics remains lacking. In this study, a platinum microheater with dimensions of 49 μm×49 μm is fabricated using micro-electromechanical systems technology. The microheater is immersed in supercritical carbon dioxide at 8 MPa and 22oC to investigate the effects of microheater orientation and heat flux on the bubble-like dynamic behavior and the associated heat transfer characteristics. Under steady heating and single-pulse heating conditions, the surface temperature variations of the microheater and the bubble-like growth process are recorded using a high-speed data acquisition system and a high-speed camera. To obtain the bubble-like evolution characteristics, the image sequences from the high-speed camera are processed to accurately extract bubble-like contours, and the volume and surface area are calculated based on the disk integration method for solids of revolution. Under steady heating, regardless of whether the microheater is oriented horizontally upward or downward, the surface heat flux increases monotonically with wall superheating, while the heat transfer coefficient shows a non-monotonic trend, first increasing and then decreasing. At low wall temperatures, natural convection dominates heat transfer. As wall temperature rises, convection intensifies, significantly enhancing heat transfer. When wall temperature reaches the pseudo-critical temperature, pseudo-phase change occurs in the near-wall fluid, leading to the formation of bubble-like structures on the microheater surface. However, due to the absence of surface tension, the bubble-like structures formed under steady heating adhere to the surface without detaching, thereby hindering heat transfer. Moreover, the heat transfer coefficient in the horizontally downward orientation is lower than that in the horizontally upward orientation, a trend consistent with observations in subcritical boiling.Under single-pulse heating, the pseudo-phase change process is highly sensitive to thermal perturbation. Once the pulse is applied, the microheater's wall temperature responds rapidly, and bubble-like structures become observable after approximately 1 ms. When the microheater is oriented horizontally upward, the bubble-like structures exhibit a three-layer distribution: a pseudo-vapor film at the bottom, a pseudo-vapor column in the middle, and a mushroom cloud at the top. In contrast, when oriented horizontally downward, the morphology of the bubble-like structures develops into a flattened shape. This study introduces the concept of "evaporation momentum force" to explain the growth behavior of bubble-like structures. At the initial heating stage, the structures grow rapidly. However, as the pseudo-interface expands, the increasing evaporation momentum force increases the adherence of the bubble-like structures to the wall. Together with interfacial heat loss, this effect makes the pseudo-interface expansion rate decrease rapidly and eventually become stable. Furthermore, our experiment reveals for the first time that the dimensionless volume change rate of supercritical bubble-like structures is always equal to the dimensionless surface area change rate, and this growth law holds true under different heating orientations and heat fluxes. This study uncovers key dynamic characteristics of supercritical bubble-like growth, providing experimental evidence for a deeper understanding of the two-phase heat transfer mechanism in supercritical pseudo-boiling.