well first I prefer to inform all of you that I usually speak french and that my english may be somewhat shaky from time to time.
When I started to be interested in abstract comics, I took them as a way to investigate the intrinsic narrative power of the language of comics and its tools (frames and speech balloons). I tried to see whether it was possible to tell stories with a very reduced "vocabulary", a little bit in the spirit of Georges Perec when he wrote his novel "La Disparition" without using the letter "e", which is the most frequently used in french. The stories I (tried to) tell involved "characters" (for example squares and circles) and were in a way "concrete" stories, the abstract characters could have been replaced by realistic ones in a lot of cases (as seen in my pages in the Anthology). They are therefore quite different from most of the material that has been posted here, where the narrative content is more related to an esthetic progression or feeling, more in the spirit of poetry than that of a short novel. (I know I am simplifying much, but it is just to stress the different approaches.)
Later I decided to try to push idea as far as I could, that is, tell stories ("concrete" ones) using only the syntactic elements of the comics language: speech balloons and frames. (I know that there are comics without frames and/or without speech balloons, and some other medias use frames and/or speech balloons, but anyway I think that these two syntactic elements are used in comics in such a specific way that they belong to its language in an intrinsic way.) What I found interesting is that the same element, say a word balloon, may be used as a character, then as a syntactic object, then again as a character, etc.
It is however true that this kind of stories are not properly abstract, as nothing but syntactic elements are depicted, so we should maybe call them "syntactic comics", or "syntactical comics", but I find in them an interesting experimental playground worth of more investigation. I have put below the first 5 pages (of 22) of my last story of this kind.