An update to the thermochromic cobalt(II) chloride equilibrium demonstration is described. Filter paper that has been saturated with aqueous cobalt(II) chloride is heated for seconds in a microwave oven, producing a color change. The resulting pink and blue map is used to colorfully demonstrate Le Châtelier's principle and to illuminate the hot spots in the microwave oven. The demonstration is a quick, easy, and colorful way to introduce Le Châtelier's principle to students in high school or general chemistry courses.