AI may make an apparently sharp jump in intelligence purely as the result of
anthropomorphism, the human tendency to think of "village idiot" and "Einstein" as the
extreme ends of the intelligence scale, instead of nearly indistinguishable points on the
scale of minds-in-general.  Everything dumber than a dumb human may appear to us as
simply "dumb".  One imagines the "AI arrow" creeping steadily up the scale of
intelligence, moving past mice and chimpanzees, with AIs still remaining "dumb"
because AIs can't speak fluent language or write science papers, and then the AI arrow
crosses the tiny gap from infra-idiot to ultra-Einstein in the course of one month or some
similarly short period.  I don't think this exact scenario is plausible, mostly because I
don't expect the curve of recursive self-improvement to move at a linear creep.  But I am
not the first to point out that "AI" is a moving target.  As soon as a milestone is actually
achieved, it ceases to be "AI".  This can only encourage procrastination.