Dallol is in the the Afar (a.k.a. Danakil) Depression at 430 feet below sea level. The lowest point in the depression is 515 feet, so Dallol is only 85 feet higher.
In the same region, Assab, Eritrea has an average dew point of 84F in some of the summer months. Given the average temperatures of over 100F in the summer, that's pretty nasty.
Luckily much of Ethiopia has a pleasant climate, because of elevation. If it weren't for the pollution, Addis Ababa (elevation just over 8000 feet) would be a contender for having the most pleasant climate in the world. It has only hit 90 there once and have hit freezing only twice. In the coolest month, daytime temperatures average 69. In the hottest month, daytime temperatures average 78, with most of the year in the low 70's.
On a side note, the highest dew point may belong to Dhraran in Saudi Arabia, with 95F (actually temperature of 108F). The heat index was 176F(!) that day, which may be the highest in the world.
Bankok Thailand is another place with oppressive heat/humidity combination. Temperatures don't get nearly as hot as on the Arabian Peninsula or the Sahara an the land west of the Red Sea, but the humidity and heat are constantly oppressive.
Back when I was young and would travel on the cheap, I spent time in Bankok trying to sleep without air conditioning. Because of the humidity and sweat, most bed mattresses are covered in plastic. I would try to sleep by soaking myself, but the humidity was so high that the water wouldn't evaporate. People living there are used to it, but I don't think I ever got a good night sleep the whole time I was there.
I visited Dubai once (in summer) several years back. I'm never doing it again..pure hell.