Bubbly or foamy urine is often a sign of protein in the urine. This isn't really normal, but could be due to several things. It could be due to an infection, or to a damaged kidney. Do you have some sort of pre-existing condition that would make you think it is kidney damage? You should definitely see the doc.
Since you are a male; just a thought....after you go, and see these bubbles, if they disappear fairly quickly, it's nothing to worry about, it's only caused by the distance from the stream hitting the water But if the bubbles look "foamy" and sit a longer while in the bowl, it could be of significance.