I have an 07 charger, the water tank has recently been bubbling I'm not sure why because of course it has water and the temperature meter doesn't go up it just stays a little less then half of the cool side. So I'm not really sure it this is normal or if something is wrong with it.
It all depends on the amount of bubbles which are occurring. If there is a large amount with steam involved, I'd be worries about it. If it's just a small amount of bubbles and nothing adverse happening, I think I'd be less likely to be worried about it. This could be just a normal thing.
On the other hand, it could be that the radiator cap is becoming weak and allowing more coolant to be pushed into the overflow. If you've never had to change the radiator cap, this might be a good time to do this as a maintenance item.