Bubbles in urine is known from the period of Hippocrates(the father of medicine) and is characterized by significant loss of proteins from urine. As a result the surface tension of water in urine is changed leading to the formation of bubbles in urine or foamy urine. Normal values are up to 150mg of protein per day. Although it may be a sign of loss of significant amount of proteins in urine (nephrotic syndrome), it does not necessarily mean that a kidney disease is present. You should check it right now with a urine dipstick to assess the loss of proteins from the urine.