I don't understand why sodium chloride will precipitate from a saturated aqueous solution when sodium nitrate is dissolved in this solution.

Any clues?

I think I know why. Can someone verify my answer please.

My Answer:
Sodium chloride equilibrium is being established within a solution that already contains Na ions. The result should be that the position of the NaCl equilibrium is "left shifted" from its normal point. Therefore the dissolution should not proceed to the right as much as in pure water. Therefore more of the sodium chloride should stay in its solid form.

Sounds sensible to me :)