Cleaning white bubbles on induction stove
I have an induction stove and have had similar marks. I think rumtscho is right; these are mineral deposits from water. Water gets between the surface and the pan, most likely because the base of the pan was initially wet (spillage from the pan will mostly end up beside it, and only areas directly under the pan will get significantly hot), the heat of the pan evaporates the water, leaving dry deposits.

There is some good advice on cleaning glass stovetops from eHow, which suggests leaving a "[vinegar-drenched] paper towel on the stove top for an hour", and using ceramic cooktop cleaner if still present.

But I've found these marks can be mostly prevented by making sure the base of your pan is completely dry before putting it on the stove.