The hose will have popped off one or both of the headlight washers - you can get to them by taking the fog grilles off. Probably the NS. When it comes off, it'll spew out enough washer liquid to put the light on and then the headlight washers stop working (and the leak stops), screen wash still works until the tank is empty.
The washer system is a bit of a lash up, I'd recommend adding a jubilee clip or two.