In Page notification in ms crm 2013 

Case 1: Navigation to/from existing records – notification

When navigating away back and forth from new records, if there is any change made to its
fields, then an in-page notification is displayed as a warning.

Case 2: Navigation to/from new records – notification

When you navigate away back and forth from existing records, if there has been a change on
the form as well as some related error, then an in-page notification is displayed as a
warning.

However, if there are no errors on the form, then an auto-save occurs to update unsaved
changes when navigating away on existing records. This will occur regardless of whether
the auto-save feature is turned on or off.