Batteries explode as a result of gross overcharging of the cells. This happens one of two ways. First, the battery may have one or more cells internally shorted, which raises the voltage applied across the remaining cells. Second and more often, the voltage regulator on the alternator has failed or the rectifier in the alternator has failed.
I suggest you install a new battery then meaasure the running DC voltage across it with engine at 1500 rpm. If it rises above the low 14s your regulator is bad. Assuming you pass that test switch your meter to AC volts, and the reading should drop to 0.05 volt. Any reading above 0.1 volt indicated a rectifier failure.