These situations happen a lot around me since I always bring my lunch to the school. It is not just plastic warp, but my plastic container lid too. Unlike Why does plastic wrap grow, then shrink, then grow again when microwaved?, it happens even when I am only microwaving my lunch, which doesn't contain a lot of liquid. It also happened when I microwaved my steaks, which are partly submerged in meat juices and other sauces, in a glass bowl with a plastic wrap on the top. The plastic warp "wrapped" against the steaks, but when I started to remove the wrap, there was no hot gas shooting out.
I am not getting the answer the aforementioned question provided since I don't understand how can the air inside the microwave and inside the container decrease so rapidly, and the "superheating" they mentioned is only about liquid at around boiling temperature. So could any one help me out here?