You can create a javascript popup that runs when the user has modifyed the work with this line:
window.onbeforeunload = function(){ return 'All unsaved Work will be lost.' }
The popup will look something like this
Confirm Navigation
All unsaved Work will be lost.
Press OK to continue, or Cancel to stay on the current page.
Use this line to prevent the popup once the user saves:
window.onbeforeunload = null;