Hi,
I've seen large electrolytics blow out their top and bend 1/4 inch thick copper buss bars with no problem. Overvoltage does it, and the more energy stored in the cap the more energy can be released during the failure. Since energy in a cap is proportional to the square of the voltage, the explosion gets 4 times worse for every doubling of the voltage.
The caps i was talking about where 400vdc if i remember right, probably 10000uf each, in a bank of maybe 8. It was a long time ago so i dont remember all the details...used in a high current three phase DC power supply with hefty rectifier diodes to match.