http://www.youtube.com/watch?v=rM2x-Fp3Fig&feature=related

 As you can see, oscillating chemical reactions can be very very interesting.  The Experiment, "Now You See It, Now You Don't" involves using different kinds of colorless substances and adding them into another colorless substance.  When you mix them, a chemical reaction occurs and causes the mixture to change colors.  It will continue to change colors for a minute or two.  The link above shows the change in color and how fast it occurs.  Interesting!!