We like to make tea by the gallon and to get the “smoothest” result, boil the sugar in the water initially, before adding additional water and the tea. This evening, the tea project was somewhat interrupted with other supper-time activities, and I didn’t stir the mixture. When we noticed the result later, what greeted our curiosity was a boiling liquid in two levels – the boiling was from the bottom of the pan up about half-way. No bubbles reached the surface. It was quite an interesting appearance. My best guess is that the varying densities of the sugar-water under the straight water made it possible.