Bind a valid class object pointer to boost::function<>fn. What may happen if invoking the `fn` after the object has been destoryed?

Bind a class member function and a valid class object pointer to boost::function<>fn. What may happen if invoking the fn after the object which the pointer pointed to has been destroyed? Are there some potential problems that I should be aware of? Domo code snappet:

 class CTest
 {
    public:
         int demo(void){}
 };

 
 int main()
 {
    boost::function<int(void)> fn;
    {
        CTest ins;
        fn = boost::bind(&CTest::demo, &ins); 
    }
    fn();
}