In large countries the reverse is true - rather than buying currency of another stable nation to back their own currency, they sell bonds to other countries and use that to print new money. This only works if people think you're going to pay back your bonds and interest when they mature.
It's essentially the same thing but the risk is placed on those who purchase the bonds, rather than on the gov't who buys the currency.
It used to be that countries would back their currency with gold, but the US stopped doing that in the last decade, and many other countries have followed suit.