You'll probably find at some point that you need to enter some text below a nested table but it's not clear how to move out of the nested table if there isn't already text immediately beneath. The answer is as follows:

Position the cursor in the last cell of the last row of the nested table.
Press the 'Ctrl' and 'return' keys at the same time - the cursor should now move to a new paragraph beneath the nested table.   _{Your Comment}