Eli5: Why does water expand while freezing, and what would happen if it was frozen in pressurized enviroment/container that cannot expand?

Question

Eli5: Why does water expand while freezing, and what would happen if it was frozen in pressurized enviroment/container that cannot expand?

In: Physics

Answer 1

This is why pipes burst. The pressure the pipe puts on the water prevents it from freezing. When the pressure exceeds what the pipe can hold the water freezes all at once and pop goes the pipe.