If the veneer is what's bubbling, you need to get it glued back down before a light sanding. A thin cyanoacrylate (super-glue) can work well for this, especially if you make tiny slices with a utility knife in each bubble before applying the glue. The thin stuff will wick into the bubbles, and then you can press em down with a caul (flat piece of wood) covered with plastic to keep it from being glued to the veneer, and some clamps for pressure. Let it dry overnight, don't use accelerator. Lightly sand and refinish.