Not at all advocating for disabling any of the safety features on a residential water heater as they are very important. However, in most home type environments, something will usually give in the plumbing system before the pressure gets high enough to blow the bottom out of a water heater.
The heater on MythBusters was not connected to a faucet, toilet or anything else so the tank was the weak spot. Normally the tank is the strongest component in the system. A tank shooting up like a rocket does make good TV.
To the OP,
A lot of times problems with refers, water heaters and furnaces can be resolved by simply removing and reconnecting all the spade lugs and plugs on the device. Those connections are pretty much exposed to the elements and tend to corrode a good bit. Reseating improves the electrical connections.
