We have noticed whenever we are running our dishwasher, or anything with hot water in our kitchen, that it sounds like a pipe making a popping/clicking sound. Our hot water tank is in the attic, so I image the pipes run down one of the walls in the kitchen. The popping sounds like it's coming from around the ceiling area where the pipe would come down the wall. Is this normal or anything to be worried about? Is there anything to prevent this popping sound? Thanks.