What formula changes between purple and gold?

When I went to my state university, I was shown an awesome presentation where he mixed a few different chemicals, all I remember is that there was iodine involved, and not only did it suddenly turn purple, like he had shown us before, but this time, it cleared and turned gold, then suddenly changed to purple again, and this cycle continued for about 5 minutes. It was WAY cool. I really want to be able to do it in my chemisty lab, since my school colors are purple and gold. So, are there any chemists here on Yahoo that can help me?