He Trow Some Sodium Metal Into A River...What Happened Is Mind Blowing!
Frostburg.edu: “Sodium has a density of only about 0.97 g/mL, so it floats on water. The reaction produces jets of hydrogen gas below the waterline; this is what propels the sodium around the surface. The reaction releases heat, and as the sodium and the solution warm up, the reaction goes faster and faster. If the sodium gets trapped on the water’s edge or against some other obstacle, enough heat can be generated to boil the water around the metal and actually melt the sodium.”