Firefox middle click

After discovering the way to close down the last tab in Firefox with a middle-click; some odd things started to happen. I would close tabs only to find new tabs opening up with places I'd already visited and left. I think now I've solved why - middle-clicking the new tab button will open the most recent in your "Recently Closed Tabs" history, keep doing it and it'll work it's way through the list. That's actually pretty neat.