This work deals with the dynamics of rapid-boiling of a droplet, at medium-high superheat, rising in a host liquid environment. It considers the heat transfer, the superheat consumption and the hydrodynamics of the droplet as it boils. In the course of the research water-column experiments were conducted, and results are shown. Superheating was implemented by the sudden depressurization of the ambient liquid. Boiling was very rapid, concluding within several milliseconds, and high heat fluxes across the interface were obtained. Additionally, certain critical times in the boiling process were predicted and defined, and a novel criterion for the end of rapid boiling (liquid film collapse), is proposed. These defined critical times agree well with measured points of change in the boiling dynamics. From these results and analysis a deeper understanding of the three-fluid rapid boiling at medium-high superheat has been established, for the first time. In addition, various initial conditions were tested and their effect established qualitatively. This form of boiling, though being very rapid and sustaining high heat transfer rates, is non-explosive in nature, and therefore more designable and widely applicable.