Hi, guys,
As we have studied in our class, ionic compounds are usually solid. Why?
Long pause.... cos ionic bonds are strong rite!!! Because ionic bonds are strong, large amount of energy is needed to break these bonds in order to turn the ionic solid into liquid state.
Now, not all ionic compounds have high melting point. There are actually things called 'ionic liquids'. As the name implies, it is an ionic compound but is also in liquid state.
How is that possible? Again, it has to do with the strength of the ionic bond. In ionic compounds where there is a large difference in the size of the ions (i.e. one big ion and a small ion), the ionic bond would be weaker. Hence, this results in the compound existing in liquid state under room temperature.

Now, these ionic liquids are useful stuff. One of the latest application is to use it as a substitute for mercury and alcohol in thermometer.
Read
this for more info.
Enjoy!
Picture from Chemical Technology