I've had a few electrolytics pop in my time with electronics. First I had a power supply with a shorted pass transistor (linear regulator) and hooked up an old car clock. After trying to get it to work (not thinking of an overvoltage problem) the electrolytic popped. Second incident was with a power inverter. Plugged it in and the cheap capacitor popped immediately. I was lucky that they were enclosed in a device at the time as the first one definitely would have gone flying.