There are thermo-shrinking plastics, commonly used in electronics, which stay shrunk after cooling down. There are thermally expanding foams. The closest to 'expanding when cooled' I know is water, with ice expanding, but only by a small margin, a scarce couple percent.
Is there a material that would start expanding significantly when cooled? May shrink back when heated, or may stay expanded. It doesn't need to be as forceful as ice (which can explode rocks) but it should have at least 30% expansion ratio, the more the better.