I introduce holes with a couple of (transparent) bottles of shampoo. Take
one that is mostly empty and turn is over - watch the shampoo flow down to
the bottom. Then take a nearly full bottle and turn it over - watch the
bubble rise.
Is something moving up in the second case? Well, not really - shampoo is
flowing down in both cases, but it seems like a completely different
phenomenon. And it is certainly easier to treat the motion of the bubble
(which moves smoothly) rather than the actual shampoo (which has many parts
each moving a short way and then stopping).