For that, the hose must have been such a tight fit or the pressure so great that the old fluid might have not have been coming out of the top. But if you're lucky, all that has happened is that the plug-in pump at the base of the washer reservoir has popped out due to the pressure.

You'll probably have to jack it up, take the wheel off, lay the wheel under the suspension to protect you and the car if the car comes off the jack, then remove the wheel-arch liner. The plug-in pump shold pop back in.