How to force EPRNext to show error message when it gets disconnected from server?

Recently I have observed that when we are working in ERPNext sometimes the connectivity to server is lost.
At that time when we try to save a Doc it just plays the Bing sound without showing any error message as to the cause of problem.

How can we force ERPNext to show the user a message saying Connection timed out or Connection to server is lost or something like that?