The Miracle of Color         While soap bubbles are miniature marvels of physics, their colors are equally fascinating due to an iridescent quality that results in a change of color over their limited lifetime. This is due to how light is reflected from both the inside and outside surfaces of the bubble. The surface of a bubble is constantly changing thickness due to drainage or evaporation, resulting in change of light reflection. As the light hits surfaces of the bubble, some of it is reflected off of the outer surface of the bubble, resulting in changes in color. A fraction of the light passes through the outer layer, reflecting off the water layer or the inner layer of soap. The visible color is dependent on the interference between the two rays of light. Constructive interference creates brighter  colors while destructive interference results in dimmer colors. As the bubble get thinner and thinner, more and more destructive interference is exhibited which is why, the precise moment before the bubble pops, it appears to be black.                                                                                                                                                                                                                     http://www.webexhibits.org/causesofcolor/15E.html