Last night, about 1030-1100pm, we were sitting in the living room watching a DVD and heard this loud 'BOOM' - it was in the distance, but loud, and still near enough to rattle our windows. This isn't too uncommon. There are military around here and they occassionally blast things. But of course, we will likely never know what shook the house. Unlike in the US, where you can expect such a loud noise to make it into the news - either immediately, or at least by the next morning - it is rare to get an explanation about anything here.
Brad and Brian heard a series loud blasts while Honor and I were in DC last year, and it wasn't until several days later that they found out that a propane tank truck in Giza (about 4-5 miles away) had blown up. We'll see if we hear anything!
At least it didn't wake the kids - today is their first day back at school.