chaintooheavy:

What really happens is that the bottle were really still while the water chilled, meaning that the temperature of the water dropped below freezing while still remaining liquid. By agitating it, it starts a chain reaction causing the water to freeze all at once. The “agitation” and /or “chain reaction” is called a “catalyst”. The water is on the brink of freezing, but it needs activation energy to start the reaction.

Science, fuck yeah.