So, I love watching MythBusters, they have some fascinating times showing what can happen and why it is important to check and maintain your home's appliances, and functioning units. In this case they show what can happen when a water heater does not release pressure because of a faulty temperature and relief valve.
This can and does happen and one of the best ways to prevent this as a homeowner is to routinely check the status of the water heater. Making sure there is no leaks and if there is a leak or drip to have it checked out by a professional who knows how to repair the water heater. It is just one of the checks a prudent homeowner checks on frequently and is recommended every 6 months.