On the 700 series, before you go to all the trouble of disconnecting the washer nozzle hoses, try to dislodge the grunge by inserting a straight pin (or staple as I believe ipd suggests) into the nozzle. Works most of the time.

If that doesn't work then try disconnecting the hoses at the little black plastic check valve and blow compressed air into the nozzle then into the hose. If more serious cleaning is required then remove the nozzles by pinching in the two plastic tabs on the underside of the nozzle, kinda tricky.

To prevent this from happening again you need to put a filter in the washer line. Volvo has one just for this job and so does ipd (about $5). I used the smallest, cheapest fuel filter I could find at my local auto parts supplier (just check the hose size). When you add a filter you may notice a slight delay starting the squirt.