$$Molarity (M) = \frac{Moles of Solute}{Liters of Solution}$$

In this case, we have 3.0 mol of CaCl2 and 0.500 L of solution.

$$M = \frac{3.0 \ mol}{0.500 \ L} = 6.00 \ M$$

Therefore, the concentration of the CaCl2 solution is 6.00 M.