In water, pink $[\text{Co(H}_2\text{O)}_6]^{2+} + 4\text{Cl}^- \rightleftharpoons [\text{CoCl}_4]^{2-} + 6\text{H}_2\text{O}$ is endothermic, and $[\text{CoCl}_4]^{2-}$ is blue. What happens when the solution is warmed?