Wichita's hard water is the biggest factor in water heater life here. Calcium precipitates when water is heated, settles as scale on the tank bottom, and forms an insulating layer between the burner and the water. The heater works harder, runs longer and fails sooner.
Rumbling or popping from the tank is water trapped under that scale flashing to steam. It is a sediment problem and it is worth acting on before the tank fails rather than after.
Not everything is worth repairing. A thermostat, an element or a thermocouple is a straightforward fix on a heater with life left. A leaking tank is not repairable at all, and we say so rather than charging to look.
Technician insight
The anode rod is sacrificial and nobody checks it. Once it is spent the tank corrodes from the inside, and in Wichita water they go faster than average.