You can imagine it physically.....just think like this..
There are Na
+ ..he has its lover that is Cl
-...they came close to each other and formed a bond..when you will dissolve it in the water...water molecules are the enemy of their bond....they will try to create some misunderstanding between them....but their bond is just perfect ...Na and Cl do not care about the rumors.....they are just enjoying their relationship..
But when you add more and more water i.e. more enemies then perhaps the bond will breakdown..
I think i should give an example of CH
3COO
- and H
+..coz NaCl dissolve readily in water..
Talking technically....
It is just an equilibrium reaction
Salt + Solvent
Ions
When you add more and more solvent then equilibrium will shift forward to minimize the stress on it or to gain more stability....