The Boston Children’s Museum hosted its “Boston Grown-Ups Museum’’ party on Wednesday night. More than 800 mature (and not so mature) adults bought tickets to the event, which allowed the so-called grown-ups to run around and play in the museum without kids. . . . The very next day (Thursday), grown-up actress Sandra Bullock, who’s in town to film the comedy “The Heat,’’ was spotted having a bite at the Children’s Museum location of Au Bon Pain.