If you leave a glass of Pepsi out for a few hours, it goes flat. But what if you left it out for a LOT longer than that?
Someone did a time-lapse video and left a glass of soda out for 105 days. You can see it slowly evaporate. After about a week, mold starts growing on the top. And by the end, it’s just sludge at the bottom of the glass.
(Search for “Cola TimeLapse.”)