An experimental investigation of thermal interaction of molten metals with cold liquids was made using measurements of transient temperature, pressure, and reactive force; postexperiment microscopic, metallographic, and chemical investigations completed the results. Thermal explosion, film boiling, and inverse Leidenfrost phenomena were considered. The origin of “jets” of small particles from the main particle was found to be a triggering mechanism of thermal explosion. Thermal explosion can be a phenomenon of coupled fragmentation and vapor explosion. Fast solidification was recognized as the main process that influenced fragmentation of the hot metal.