Turino writes: "At the airport,said paperwork,your residents' permit and your foreign experts' certificate will be taken from you."

This is a prime example of misleading information either through ignorance or a wish to scare.
First of all, a current Residence Permit in ones passport acts as a multiple entry/exit visa. Provided that it is in date, a person is free to travel to and from China at will. How for instance would the airport immigration officer know that you are breaking your contract ? Unless they have red flagged your name following information from the PSB, you can leave without hindrance. The most that will happen is a cancellation stamp will be placed on your RP should they be aware that you have not complied with your obligations.

If you are intending to leave your school go home and not return, do so without advising the school. The Foreign Expert Certificate belongs to the school or employer so leave it in your apartment or post it back to them from the airport.

Should you be intending to simply change jobs or return to China, other advice will be relevant.