Why does 100 cm cubed of water turn into 109 cm cubed of ice?
This is because when water changes from liquid to solid ice, it tends to expands. The molecules that are in solid ice can be positioned in different ways, called phases, depending on the temperature and also the pressure.
yea what this guy said ^^^^
Maybe because the air bubbles in the middle of ice cubes take up space?? Not sure, but I thought I'd take a stab at answering.