Investors have been flocking to emerging market bonds in recent years, but the party may have gone too far, some experts say.

"I hate to say this, but in five years' time a lot of this will get hammered," one investment banker told the Financial Times.

The peak of the boom may turn out to be Rwanda's $400 million bond issue last month for a convention center, the Times noted.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.

Investors clamored for a piece of the action, even though much of the country's budget comes from foreign aid, and some of that was withheld last year after Rwanda was accused of backing rebel fighters in the Democratic Republic of Congo.

One senior banker who mulled marketing the Rwanda bond issue told the Times he declined because "we couldn't look investors in the eyes and tell them it's a good deal."

But the search for yield in a low interest-rate world may continue to boost emerging market bonds.

"We are worried about some of these countries, but current momentum supports buying their bonds," Gregor MacIntosh, head of sovereign debt at Lombard Odier Asset Management, told the FT.

"We'll just have to be nimble when things turn."

Investors are even starting to look farther afield for opportunities.

"There is return potential from accessing this new generation of [frontier] countries on an opportunistic basis, increasing allocations within a more mainstream portfolio when conditions are supportive," Jonathan Mann, head of emerging market debt at F&C Investments, told Investment Europe.

"Examples of these countries include Angola and Azerbaijan."

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.