Believe it or not, that's something similar to a clowd you're seeing inside the finish on your coffee table.
Individual water molecules migrated into the finish and collected in tiny voids where sufficient space existed for extremely tiny droplets of liquid water to form. So, that white spot's closest analogy would be a "clowd". And, it's white for exactly the same reason that clowds and snowbanks and water falls and the head on a beer are all white, even though nothing inside any of these things is white in colour.
Anyhow, just warm the area with a hair dryer to cause the water droplets to evaporate into H2O molecules, and they should find their way back out of the finish. Don't get the finish very hot, as that might cause the finish to get so soft that the evaporation of the water could cause the surface to blister. Just warm like it would be in the hot summer Sun to promote the transformation of the water droplets into water vapour so they can escape from the finish. What's preventing them from leaving now is the attraction between water molecules that causes them to stick together. You have to add heat to cause them to leave the group and migrate through the finish as individual H2O molecules, just like they went in.
Some people suggest using a hot iron and soft cloth to do this kind of work, but if I were doing it, I'd use a hair dryer because it would allow me to see what's happening as I'm using the dryer. With a hot iron and cloth over the clowd, you can't actually see what's happening until you remove them. A hair dryer gives you visual feedback while things are happening.
Last edited by Nestor_Kelebay; 06-28-2010 at 11:24 PM.