When Spanish people talk about their "boss" they say it is such a way that it often sounds like "box" (caja). It is important to try to correct this because when you are talking to native speaker they may misunderstand you. So when you are talking about your "boss" you need to pronounce it: "BOSSssss".
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.