There’s nothing like sitting back with a cold one and listening to your canned goods seal themselves in the next room. Ponk. Ahhhh…there’s another one that’ll be good ’till spring. For those of you who’ve never had the satisfaction, canned goods make metallic popping sounds as they cool. It’s all those contracting gasses you see. The process of boiling the closed jars causes the food and the gasses on the inside to expand. This has the effect of pushing out small quantities of air. As the jars cool the food and gasses contract, creating a vacuum that pulls the metal lid on the top inward, finally sealing it. Clink! Done.