Popper is quoted in Relativism and the Social Sciences, by Ernest Gellner, ch. 1, p. 5.:
Many years ago I used to warn my students against the widespread idea that one goes to university in order to learn how to talk, and to write, impressively and incomprehensibly. At the time many students came to university with this ridiculous aim in mind, especially in Germany ... most of those ... who ... enter into an intellectual climate which accepts this kind of valuation ... are lost.
Thus arose the cult of un-understandability, the cult of impressive and high-sounding language ... I suggest that in some of the more ambitious social sciences and philosophies, especially in Germany, the traditional game, which has largely become the unconscious and unquestioned standard, is to state the utmost trivialities in high-sounding languages.
Some of the famous leaders of German sociology ... are ... simply talking trivialities in high-sounding language ... They teach this to their students ... who do the same ... the genuine and general feeling of dissatisfaction which is manifest in their hostility to the society in which they live is, I think, a reflection of their unconscious dissatisfaction with the sterility of their own activities.
The source is given as:
The Positivist Dispute in German Sociology, by T. W. Adorno, Hans Albert, Ralf Dahrendorf, Jürgen Habermas, Harald Pilot and Karl Popper, London, 1976, pp. 294 and 296.
I think it's a misquote or incorrect citation in some way because it skips a page but never has ellipses to skip one or more paragraphs. The only time text is skipped it's within a paragraph. (It could be correct if there's a paragraph that's over a page long, I guess.)
I like the quote and I noticed its similar to Ayn Rand's view.