Regarding the gear you need for high-speed shooting, it's true that you'll have trouble getting more than a few frames per seconds if you really want to take a photo.
Or to get full HD video you'll need specific professional (thus very high cost) equipment.
But if you are willing to compromise, nowadays several cameras (usually bridges, but also even more and more point and shoot, anyway with a more reasonable price tag) offer some form of high speed video (at least 100fps). I won't give specific models but let you google or check this for example.
For video you don't really care about the trigger : you just start the recording and "explode away". But for photo, you'll also need some equipment to trigger the shot - provided the camera has some form of external trigger input. First you'd need to determine the shutter lag of the camera (how long between triggering and actual shooting) and then use some delaying circuit to first trigger the camera then trigger the explosion. Trial and error seems unadapted here, I guess you can't create so many explosions. Another way of measuring would be to shoot some fast counter (chronometer ? not fast/accurate enough ?) rigged to start at the very same time as the camera is triggered and see what time is displayed on your shot.
Or you could trigger by the sound if the camera is close enough (but mind the additional delay introduced by sound velocity ~300m/s, much slower than light and your explosion)
Then regarding the optical part, I think the "shockwave" might be more visible if lighted from an angle on the side and from behind... you don't specify whether it's indoors or outdoors, with extra lighting or not, so it's difficult to say.
If you have the opportunity, a chequered (or other geometric texture) background with contrasted colors (black and white) might help enhance the visibility of the shockwave by emphasizing the distortion.