An enlarged prostate is also known as benign prostatic hyperplasia (BPH), which is generally not associated with any prostate pain. However, an enlarged prostate can cause problems with urination.
When a homeowner turns on a faucet, the cooled water sitting in the pipes circulates to the faucet first, so the homeowner has to wait for hot water. A hot water circulation pump sends cool water in the pipes back to the water heater through a return line. A pump circulates this water through the water heater as needed to keep it hot. This continuous loop of water through the water heater ensures that hot water is always available.
You probably have sediment buildup in the bottom of the hot water heater. Pockets of water get trapped in the sediment/scale at the bottom of the hot water heater, turn to steam when it heats up, then explode causing the noises you are hearing.