My fiance opened our mini fridge and found a La Croix can inside, but it looked like this. Obviously it was not open at first, but when I first opened it it hissed and expanded slightly as if there was a slight vacuum inside. What the fuck happened? It didn't come this way from the manufacturer, nor did it undergo any pressure changes, and no other cans in the fridge did this (though many of those were beer). It was likely frozen at one point since I am still trying to get the ideal temperature for my mini fridge, but usually cans of sparkling water that get frozen just expand and then thaw normally. The La Croix in question tasted like any other but was completely flat. Where did the carbonation go while leaving the can sealed?