Pulsating water and banging noise from pipes when hot water is on in the faucet or shower in the bathroom
this is a common problem called water hammer.  its caused by resonance in the system of pipes that makes up your home water supply system.  this can be caused by trapped air, but can happen without it as well.  you have two solutions:

1)  install an anti-water hammer arrester. its a little doodad that helps to smooth out the pulses so you don't get the resonant waves running through the system.

2)  go through and mechanically fasten the pipes better than they currently are.  unfortunately, as most will be running through finished ceiling and wall cavities, this means cutting holes and patching them.