Ice Formation Humans are aware that during molecular changes, rapid expansion can and does occur.
Explosions are such a situation.
Subatomic particles bound closely to the nucleus of atoms go on the move, and bump each other during this activity, so the exploding mass as a whole requires more space. There is pressure outward. But explosions seem to be accompanied by heat, where the formation of ice crystals seems to be due to the lack of heat. Gaze at a drop of water and the same water molecules represented as fluffy snow. Snow, as the weary crews that plow roads in winter are painfully aware, takes up so very much more space.