That happened to my dad and I in his 2006 300c a few years back. We were cruising down I-75 just south of Grayling, MI with the sunroof vented, next thing we know it we hear a loud POP! and the glass just went everywhere! Pulled off at a gas station and cleaned out as much as we could. Drove it straight to our family friend's body shop once we got home. The whole back half of the car including the roof had to be repainted due to scratches from the glass in the Brilliant Black paint....NOT FUN.