You have been overly generous with successes.
The aloe-prune liquor isn't going to be magically successful. Realistically, you would have to consume a lot of prunes and aloe to have explosive effects, otherwise you simply have slightly softer poops. A prune-aloe slurry would also be hard to mistake for whiskey. Making this work should likely take a whole series of rolls: first a relatively difficult chemistry(?) roll to make some sort of laxative with characteristics anywhere near booze. Next a social roll to convince the bartender that this mystery bottle is apology booze. Finally, you'd probably need some sort of easy medicine roll/skill level to predict the effects (likely just a slightly urgent trip to the toilet).
Depending which version of Call of Cthulhu you are using, you should likely be applying penalty dice to some of those rolls.
With explosives, you should consider the difficulty and effects. Making an explosive that looks like nail polish is probably just a regular success. Making a stable explosive that looks like nail polish is probably a hard task. Having made it, you probably need to actually do something with it, which may be its own task. Depending on what time, materials, and workspace you have to work with, you should probably look at hard or extreme difficulties (and penalty dice if applicable).
Explosives also aren't magic.
As Trish points out in comments, default Cthulhu is in the '20s or '30s, and explosive technology is still immature (and dangerous).
Dynamite is absurdly powerful in CoC. it does 4d10 damage within three yards (dice halved every additional three yards). That will simply kill most entities. Unfortunately, it will simply kill most characters even more easily. Failing an attempt to throw dynamite or to rig it gets very dangerous for the user and anyone around him. Estimating quickly, a cigar box is usually about 6x6x1.5 inches inside, which is inconvenient for full sticks of dynamite, but it's reasonable to handwave that. Say you can stuff it with about 8 sticks worth of dynamite. Fusing it is going to be the exciting part: if you mess that up, you and anyone within about 60 feet are likely just gone. If you are throwing the box like a satchel charge, you will be dead (can't throw that far). If you are setting it as a booby trap, you likely need a combined explosives/mechanical repair roll, and it might reasonably need to be a hard roll (don't fumble!).
On the other end of the spectrum, the nail polish bottle is a lot less dangerous. It's also a lot less dangerous: that's about a half of a blasting cap's worth of explosive, so it's about 1d10 of damage within 1 yard (assuming it's some sort of non-electric cap, and that the character can chemistry up a useful fuse for it). That's a much more reasonable level of risk, and he is likely to even survive a failed role. The entities he wants to use it on are also likely to survive.
One final note: this is an example of a question where the system makes a significant difference. Call of Cthulhu is a grinding, punishing system, and it is simply difficult to make zany plans work. If you were playing e.g. Trail of Cthulhu, this sort of play experience would be much more normal and expected (see: What is this story I recall about an extremely long ever-changing character backstory?)