Mine are going through a phase of doing that at the moment too.
Besides getting the eggs out as often as possible, these are some of the options you can try:
*Make the nest area dark.
*When you find the next broken egg, mix some really hot chilli sauce into it and leave it insitu (the idea is they will find it, have a peck and be put off the taste).
*Check for rats! Quite often rats are the culprits, not the hens. The hens eat what the rats have left behind and this is the bit you see - the rats having done a runner before you see them.
*Change the nest area, again keep it dark.
Once they get a taste for eggs it is a habit that is hard to break.