Will it explode?
My guess is no… the pressure created inside won’t fracture the hard shell.
Why not? Assuming it’s pressurized enough, it has to be released somehow, and cracking the shell is the only way to do it unless the intact shell is porous enough to allow the steam to escape.
Maybe the shell would burn away before the pressure needed to do anything significant built up?
My WAG is that the shell will burn long before the inside is heated enough for it to explode. It’ll probably hiss and spray some fairly hot steam once a spot is weak enough though.
Having said that, if someone through one in, I’d probably stay a good 20 feet away until it did something, but I’d expect, based on campfire that people tend to sit 3-5 feet away from, it would probably take 15 minutes or so before anything happened.
You should build a campfire and try this. Make sure to drink plenty of beer first, that seems to be a requirement for this type of experiment.
What about a coconut in the microwave.
I would think the three soft spots would “give” first.
I can’t believe I couldn’t find one on youtube. That’s incredible - I was certain it would be out there already. . .
coco puffs
I will try it sometime but I don’t think it will. The shell is too porous to build up enough pressure to make it explode in a meaningful way. You would have to get enough heat to make the fluids inside boil and have the steam build up to high pressure and very suddenly rupture for an explosion. Any little crack will let the steam escape before it can build up enough pressure to explode. It usually takes a metal or hard plastic casing to do that.
I have no experience with coconuts, but I have had a similar situation with bamboo, which has sealed compartments inside it.
We were on an uninhabited island off the coast of Malaysia, you had to bring all your own food, arrange a fishing boat to bring you in and fetch you out, cook over an open fire, etc. It was idyllic and we were so grooving on it. Settled down to make some dinner, rice and fish. We two girls had spent some months cooking over open fires while traveling across Canada, so we were feeling all savy and experienced. Of course we had no grill, but no worries, we knew all about putting in a couple of similar sized logs and balancing the pot on top.
It took us some time to get a fire going but we did it, so proud we were. We were very hungry and the smell of the rice was making us hungrier still. When all of a sudden there was a mighty explosion, you guessed it, the bamboo! Kaboom, really loud. Not only did it scare us nearly to death, it dumped the rice and water onto the fire and promptly doused it. We went from feeling all talented and in our element to feeling like a couple of inexperienced boobs!
The only saving grace was there wasn’t anyone else around to see our utter defeat. I think we ate biscuits and went to sleep.
That’s my guess.
You read my mind.
This sort of thing is just the sort of thing that sounds like fun…and beer always makes idiot stunts like this better. I read this at work and thought it sounded like something I’d like to do with friends this weekend. We’ve had a pretty stressful week, so trying to blow up a coconut in a campfire with beer included might be good.
I’d like to say that the reason we won’t try is because I suddenly got all mature and stuff. The real reason is because I went to all three grocery stores on the way home and all the coconuts have been scored around the middle for easy opening. 
As a 14 year old my friends and I went through a phase of blowing things up with firecrackers (bangers in the UK)
Foodstuffs mainly, eggs, pies, soft fruit and best of all, onion Bhajis, watch them babies fly!
There was also the memorable time one of my friends poured petrol from an open bottle onto a smouldering fire “to give it a kick up the arse”…hilarity ensued.
Had we had free access to coconuts I’m sure we’d have done that as well.
And no, no-one was seriously harmed in all this but exactly how we avoided major injury I have no idea. Please god let my son be a little more sensible than I was,
I am totally shocked that there seem to be no videos of this on the internet. And yes, I absolutely want to try it, but I think I’d better wait until I make it out to the country, not try it in my little firepit in my postage stamp of a Chicago yard! 
I’m betting that it’s going kaboom. Why? Because the coconut water is sterile. That means there are no openings or cracks in the shell large enough for air and bacteria to get into, which means there are no openings or cracks in the shell large enough for air or steam to get out of. And I think there’s enough moisture in the coconut meat - just comparing it to green wood - that it won’t dry out and crack before the coconut water begins to boil. Buildup of steam = coconut popcorn.
Subscribing. I’ll be out in the country in a few weeks and, if no one has posted results by then, I’ll do it.
Make sure you try it with a fresh, sloshy coconut. No fair testing with an old dried out cracked one. 
No, there are the little soft spots where the sprouts come out. Remember, it is a seed and must open to grow.
I think much of what happens depends on how hot the fire is. At the edge of a wimpy fire and the shell may burn through first. A big bed of hot coals might be the most likely to explode. For a true scientific answer, we need to do it several ways. This is going to take a lot of beer.
I’m thinking placing it soft spots down in a well-heated pile of ash and coals, while surrounded by a roaring fire would best support the explosive result. . .
You’ll need a mature fire to heat it up quickly before the shell starts burning away. And the greener the cocnut the better. If you can find an un-peeled one, that would be best. . .