Thanks to funding from several other sources (Tuscola County Community Foundation, Michigan Space Grant Consortium, Innovative Educator Corps), we are able to expand not only the mobile Idea Lab but also to have a room setup where the one of the cart sets could be used in an open Makerspace area.
I placed food coloring in the bottom and filled them with water as I thought, why have just the tubes. Taking clear water beads from Dollar Tree, I placed them in the tubes over night. The next morning I came in to find several beads across my desk as there were too many in the tube but also that the beads were showcasing an ombre effect similar to the water with the darker beads being at the bottom. I took out enough from the top to put the corks on. After a few days, the other beads on my desk started dry back out but the test tubes did not.
Update to Original: 3 months later and the tubes still look like this.
That's Elementary Explains is a teacher with almost 2 decades of teaching experience and a technology degree who is still trying to figure out the new and unexplained.