The chili i made last night was made with deer meat as well as pinto beans, kidney beans, black beans and?

lots of diced tomatoes w/ green chilis. the seasoning i used was carrol shelby's brand .all of the beans were canned. i did not refridgerate it because it was too hot. when i uncovered it today, it was foamy and you could actually see bubbles rising from below. it was as if each individual bean was farting on its on. what did i do wrong? i've made lots of chili before and never seen this happen. there was no heat applied to the pot but it looked as if it was cooking.