We study how sovereign fiscal stress builds before macroeconomic collapses. Using a panel of developed and emerging economies from 1950 to 2023, we show that the interest-expense-to-revenue ratio strongly predicts GDP and consumption disasters, as well as hyperinflation, while debt-to-GDP has little predictive power once financing costs are accounted for. The relationship is highly nonlinear, especially in emerging economies. We develop a quantitative open-economy model with rollover risk that matches these patterns to study the impact of anticipated transitions toward higher government spending in advanced economies. The model highlights how financing conditions, monetary policy, and fiscal adjustment jointly shape macroeconomic fragility.