Purdue University has paused new enrollments in its income-share agreement program, a financing mechanism both praised as a bold experiment to make college more accessible and criticized as a predatory scheme that traps students in dodgy and expensive contracts. Known as Back a Boiler, the program was quietly paused earlier this month, with a message posted on Purdue’s website around the same time that President Mitch Daniels announced his forthcoming retirement and a successor was selected through a secretive search process.