Those explosions are most likely not random. I played like 5-6 hours today on heatrs & minds and because I had some questions about the IED's I took a look on the ALiVE Wiki. You need to make the difference now between actual IED's and explosives.
IED's 
They usually look like this and players who have a mine detector who get in close proximity the metal detector will play a sound that sounds like
this. The sound can also be heard by people who are around the guy with the metal detector. Right now everyone can use the detector by the way. But my personal suggestion is that only the engineer or another dedicated point man should have them to avoid confusion when 8 mine detectors at once play the sound. Those IED's can be disarmed by the engineer over the vanilla action/scoll wheel menu. There is a chance that the first disarm will fail and that brings up two wired for the engineer and he has to make something that looks like a 50/50 decision (which seems a bit silly if you afk me).
There are also vehicle borne IED's they are located at the underbody of vehicles. So far I have not encountered them on hearts & minds yet.
The other thing are explosives. They look like the standard demo blocks from vanilla and as far as I understood it they were introduced in the last ALiVE update and are maybe placed by civillians who are supporting the insurgency.
Quote:
As the armed insurgent cells complete objectives, the security situation will deteriorate and peaceful civilians are turned into
hostile civilian insurgents. If there is an IED Factory, Weapons Depot
or Recruitment HQ in the area, occasionally civilians will be coerced
into to picking up weapons or explosives and sent on missions in support
of the insurgency. Security forces can detect these civilian
insurgents by monitoring their movements or stop and search.
- Sabotage - insurgents will collect explosives from a Weapons Depot and set out to destroy or damage civilian infrastructure targets such as
factories and power stations in order to destabilise the security
situation. They will attempt to place 3 to 5 explosive charges near the
building before moving to safe distance and detonating. If they are
successful, this will have a high impact on the hostility level.
- Rogue Shooters - coerced civilians will collect a gun from a Weapons Depot, then blend into the local civilian population until a security
forces patrol shows up.
- Suicide Bombers - similar to rogue shooters but spread themselves over a wider area.
I am not 100% sure how they work, there is no option to disarm them. However you can shoot them or place a secondary charge that will cause them to explode. This however seems a bit weird as solution since you would actually do what the enemy wants in the first place. I also had two situations where they exploded when players walked/drove over them. I also had one situation where I am sure that those sabotage guys blew up a car and damaged a civilan compound today.
