Peepaw

Never seen one blow myself buy a co-worker had one blow up in his face back in the 70's. It blistered his face pretty badly as he was overcharging the battery when it went. Nothing like scalding hot battery acid on the face.
I've worked on cars since the late 60's and have a pretty good grip on battery safety. That being said, it only takes one bad mistake to blind you for life.
Wear eye protection.
Always remove the negative cable first and install it last.
Keep cable ends clean, tight and in good repair.
Keep batteries charged, batteries don't like being dead.
Keep and eye on the water levels, more so in the summer.
Use distilled water.
Respect the batteries, believe it or not, under just the right conditions there is enough stored juice in a 12 volt auto battery to kill you.