The watter mixed with the MRE Heating Pack makes gasses, the gasses expand the bottle to the point of breakage, so when the bottle "Decompresses" it sounds like an explosion simple since here... But loads of fun!
Please excuse the Number of steps, its easier then you think.
Warning - Use at own risk! The gasses from the MRE Heating Pack is very flammable, so I strongly suggest keeping it away from a open flame..
Also, Check with you town law to see if it is legal!
Step 1: Things you need
You will need --
1-2 MRE Heating packs (use more or less for size of bottle i suggest one or two for a 18-24oz. bottle)
Plastic Bottle with screw on Lid
An some water.. (OH NO NOT WATTER!)
Step 2: First
First off, you open your MRE Heating Pack, and take out the actual heating package.. Make sure you can get outside fast, the last thing you want is for it to go off inside. But no worries, it doesn't become active until it comes in contact with a liquid.
Step 3: Secent
You can do this step many different ways, experiment and find the easiest to you, this is the method i use..
You rip the Heating stuff into long thin strips. an well you put it in the bottle.. (MY GOWD... ITS SO HARD!)
Step 4: Step 3!
Well... here is the hardest part of all... (haha doesn't get much harder then that last step eh?) But this will take the longest time to master... You add just enough water to cover about half of the MRE stuff... you can adjust to how much you use an what not it takes time to figure out how much u really need... but as soon as u add the water you put the cap on and make sure its nice and tight. then you take the bottle outside an shake well... once it starts to get hard you place it where u want and stand back and watch