Hmm, upon further reflection, the experiment I suggested would not be technically accurate because in the actual baking, there is all the other ingredients which serve to thermally insulate the alcohol, so the alcohol in the muffins will evaporate more slowly than just the alcohol in the muffin tins.

Another note is that the alcohol will continue to evaporate (albeit more slowly now that it is cool) over time, so there will be less alcohol the next day than the day you bake it.