The mass changes. That is why when you freeze a can of soda it distorts. The mass got larger when it froze. Therefore when it thaws it shrinks back to it#039;s liquid size. You can test this by putting water in a container. Mark where the top water line is. Freeze it and look where the top is. It will be above your original line. Of course the more the mass the more obvious the change.
Also some turn to gas, as in the case of dry ice, as it melts it gives off a gas.