"It pops a lot when it heats up, but has been doing that a while. "
On a gas water heater that's normally caused by sediment in the bottom of the tank. It traps pockets of water that can super heat and flash to steam, causing the popping noise. It can also be caused by water flowing through the mineral deposits and josting them around.
Years ago I helped a friend replace his gas water heater. It was LOADED with mineral deposits, to the point where it was clogging the drain valve.
Once you get the new on in place, read up on:
1. Maintaining the anode rod.
2. Maintaining the tank to remove mineral deposits.
If you keep up with those two things there's no reason why a water heater, electric or gas, can't last years longer than its "rated" life.