From the Wikipedia page on Timur Kuran:
The fall of East European communism in 1989 came as a massive surprise. Iran’s Islamic Revolution of 1978-79 stunned the CIA, the KGB, the Shah of Iran that it toppled, and even the Ayatollah Khomeini, whom it catapulted to power. The Russian Revolution of 1917 stunned Lenin, the deposed Romanovs, and foreign diplomats stationed in St. Petersburg. No one foresaw the French Revolution of 1789, not even the rioters who brought it about. In each of these cases, a massive shift in political power occurred when long-submerged sentiments burst to the surface, with public opposition to the incumbent regime feeding on itself. Preference falsification explains why the incumbent regime appeared stable almost until the eve of its collapse. People ready to oppose it publicly kept their opposition private until a coincidence of factors gave them the motivation and the courage to bring their discontents out in the open. In switching sides, they encouraged other hidden opponents to join the opposition themselves. Through the resulting bandwagon process, fear changed sides. No longer did opponents of the old regime feel that they would be punished for being sincere; genuine supporters of the old regime started falsifying their preferences, pretending that the turn of events met their approval.
Timur Kuran first identified this mechanism in a April 1989 article entitled “Sparks and Prairie Fires: A Theory of Unanticipated Political Revolutions,” which offered the cases of 1789, 1917, and 1978-79 as examples of revolutions that stunned the world. A few months later, the pattern was repeated in Eastern Europe. Kuran proceeded to explain why seasoned experts of the communist bloc were caught off guard in “Now Out of Never: The Element of Surprise in the East European Revolution of 1989,” published in 1991. These two papers, like related chapters of Private Truths, Public Lies, suggest that political revolutions and shifts in political opinion in general will catch the world by surprise again and again, because of people’s readiness to conceal their political proclivities under perceived social pressures.
Asked in an interview whether he thinks that revolutions or counter-revolutions are imminent in the Islamic Middle East, he responded that although most Middle Eastern regimes are unstable due to lack of genuine legitimacy, the required shifts in Middle Eastern public opinion are unpredictable. If Middle Eastern regimes do collapse like a house of cards, he adds, most observers will be stunned, though there will be no shortage of commentators who will say “I told you so.”