An electrolytic capacitor conducts a high DC current when it is connected with backwards polarity. I think the current causes the electrolyte to quickly get hot and boil which makes steam and an explosion.
There are non-polarized electrolytic type capacitors, and they are good when you need high capacitance without worrying about polarity. But I don't know if any products use them.
Cheap speakers use non-polarized electrolytic capacitors in their passive crossover network to keep the low frequencies out of the tweeters and keep the high frequencies out of the woofer.
Inexpensive audio amplifiers use them to couple audio frequencies.