Do condo association meeting topics need to be on the agenda?

Does the law require items discussed and voted on to be on the Agenda of an Annual Condo Association Meeting? If so, do you know what law pertains to this? We recently had a meeting and some folks wanted to bring up a topic and vote on it but it was not on the Agenda. We had 16 proxies. Those folks were not aware that a topic other than the Agenda items were going to be discussed. It just doesn't seem to be appropriate.  We live in New Hampshire.