Aluminum gives off hydrogen gas when combined with acid. Majorly explosive. However, aluminum combines with oxygen in the air to form an aluminum oxide layer that protects the aluminum. Add heat and the layer starts to erode. Hence the nonreactive pan.
DO not try..... a 2 liter bottle filled part way with vinegar, add some crumpled aluminum foil (think surface area), put a balloon on top to catch the hydrogen. Tie off balloon and ignite with a candle affixed to a long stick. DO not attempt.
