This student may be attention seeking and/or looking for your approval. In this situation, you may want to try only acknowledging students when they actually raise their hand. Totally ignore the answer when it is shouted out. When students do raise their hand, especially this particular student, make sure to point out how great it is that he or she raise his/her hand to answer the question and offer a lot of praise.

I have a student that does this all the time. I ended up meeting with him and his mom and we created a behavior contract for him. One of his goals was to raise his hand. He receives points for completing his goals and at the end of the week he gets a prize if he met a certain amount of points. We agreed that he gets three warnings before he loses the point for raising his hand. It seems to be working, not all the time, but better than before.

I have a student (or 4!) that does the same thing. I first made him aware of how many times he actually shouted out by keeping a chart in his desk. I then set a goal to decrease the number of times. If he reached the goal, there were various incentives, that he created, to choose from for meeting the goal.

I would try showing him techniques to keep answers in his head. Let him know why and how this affects others when he shouts out. Have him come up with a way he can control his impulsive comments. With guidance maybe the both of you can come up with a cool action that he can do. May he can put his hands on top of his head to block the "thoughts from coming out" or put his hand over his mouth before he feels the words coming out. When you see that he performs this correctly and you see him attempting to do it then reward. You can also make a chart of how many times in one day he shouts out the answers. Have a goal for him to reduce that amount a little each day until there are hardly any or no outbursts at all.

I think that it would be good to acknowledge the students who have their hands raised and ignoring the student who shouts out. When calling on students who have a "quiet raised hand" will praise the student and also make the student who shouts out aware of his behavior and that you aren't going to accept it anymore. This is beneficial because it gives other students praise while also making your expectations clear about how you want students answering questions.

One solution is when possible, for example in math, have the students use whiteboards to say the answer. This way he is allowed to answer but he is not calling out. Another idea is to talk to the student privately about what he is doing and see if together you both can come up with a solution.