So I tried Toot's method of making doce de leite from a can of condensed milk (see link below). I'm happy to say that not only was it delicious but there were no explosions. I ran it under cold water for about half an hour before opening it.
I cooked it in the pressure cooker for 20 minutes after the pot was pressurized. I think another 5 minutes would have helped -- the inside of the pudding was still a little runny.