Yeah, it could blow up, but only if the temperature/pressure relief fails to open. I’m assuming this is an electric tank from what you’ve said. There is a good chance that one or both of the thermostats controlling the elements have failed. Since dealing with electricity can kill you, I think you ought to get a plumber out to test the elements and thermostats and fix whatever is wrong.
However, you may be able to narrow it down a little. There is a simple test described under Tanklets, Electric water heater issues, and a ways down in the questions, below the troubleshooting walk-through, that tells you how to determine if it’s the upper or lower thermostat that is bad.